I've got a few sets of Lycra ones. They wear out pretty quick when you walk in them. There is probably not much difference in the aero benefit between either type at our more pedestrian, non pro speeds.

I have had all brands now and just have some plain lycra ones at the moment that have.....No zipper, As a veteran of over 100 TT's If you get a type with a zipper, one day, yes I have seen it happen to lots of people is that the zipper works unzipped during a tt and the the cover becomes no areo, worse that your shoeI use some light lycra ones that I strech the hem every time getting them on, but the never come loose. They get holes in them quick tho.The latex ones look super quick, but get really hotRegards Troy

Rota-M Cycling Team, Board Member of ATTA, Member of CWA, WCMCC & PDCC

Not sure if the Gore ones are TT ones or thicker cold weather ones? I think too the actual sock versions are overpriced, I mean it's just a sock, they are only ~$10pr normally, how do they justify charging $30 to cut holes in them?